The randomized, crossover study involving 16 pregnant women with type 1 diabetes compared a closed-loop insulin pump therapy with a sensor-augmented pump therapy, in a study led by Zoe A. Stewart, MD, of the University of Cambridge in the U.K. and colleagues, published in The New England Journal of Medicine.

In addition, after comparing the treatments in all the participants, the researchers followed up in a continuation phase where the women used the closed-loop insulin treatment during both day and night through the time of delivery.

Type 1 diabetes can result in myriad prenatal complications in women with uncontrolled glucose levels, the researchers noted. Because insulin requirements can increase drastically throughout pregnancy, new treatment options are needed to help manage the unpredictable nature of the disease during pregnancy.

"One in two babies born to mothers with type 1 diabetes have diabetes-related complications including preterm delivery, large-for-gestational-age babies, and neonatal care unit admissions," the study's senior author, Helen Murphy, MD, clinical professor in medicine (diabetes and antenatal care) at the University of East Anglia, noted in an interview with MedPage Today.

"Even our best current treatments have not really helped the majority of women to achieve tight control of their blood glucose levels, with most spending only 12 hours per day with target glucose levels. We wanted to investigate whether these new artificial pancreas/closed-loop technologies would allow more women to achieve tighter glucose control more safely."

A program on a tablet device monitors the closed-loop insulin therapy system, with the program identifying glucose levels and automatically administering proper dosage every 12 minutes.

Overall, the researchers found better overnight glucose control in pregnant women with type 1 diabetes with the closed-loop system as compared with the sensor-augmented pump therapy.

During the first phase of the study, which consisted of a 4-week crossover comparison, the researchers measured three main variables. Stewart and colleagues first compared the percentage of time that glucose levels were in a normal, target range (considered to be 63-140 mg/deciliter overnight) for the pregnant women, which was significantly higher in the closed-loop treatment (74.7% versus 59.5%; 95% CI 6.1 to 24.2).

Second, the team measured the overnight averages of glucose levels, which were significantly lower in the closed-loop therapy compared with the control (119 versus 133 mg/deciliter [6.6 versus 7.4 mmol per liter], 95% CI -23 to -4).

Third, the researchers examined the percentage of time that glucose levels were below a target range, which was not significantly different between treatment therapies (1.3% for the closed loop and 1.9% for the sensor-augmented pump; 95% CI -1.7 to 0.6).

There was also a significantly lower frequency of hyperglycemia and substantial nocturnal hyperglycemia when using the closed-loop treatment versus the sensor-augmented pump therapy.

The second, continuation, phase of the study lasted for the duration of the participant's pregnancies, which was up to an additional 14.6 weeks. This phase focused on the efficacy of round-the-clock treatment using the closed-loop insulin therapy. Throughout this phase, the researchers reported target-range insulin levels for an average of 68.7% of the duration. Glucose levels on average were 126 mg/deciliter (7.0 mmol/liter).

A total of 26 adverse events were reported during the study, but none as device-related.

The authors pointed out that the results build on past research on the benefits of a closed-loop therapy system as related to stable glucose control in patients. Although the sample size was small, with only 16 participants, the researchers noted that the women varied in terms of past obstetrical morbidity, allowing for greater generalizability of results.

Murphy said that follow-up studies are needed to further test the treatment in pregnant women: "We are definitely planning to do longer-duration studies in a larger number of women from a range of different maternity centers to determine whether the exciting preliminary results can be more broadly translated and may be applicable for all pregnant women with type 1 diabetes."

The study was funded by grants from the National Institute for Health Research, Diabetes UK, Gates Cambridge Trust, Jean Hailes for Women's Health, the NIGR Cambridge Biomedical Research Center, and a Wellcome Strategic Award.

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